<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			.father{
				width: 500px;
				height: 500px;
				border: 1px red solid;
			}
			.son{
				width: 200px;
				height: 200px;
				background-color: red;
			}
		</style>
	</head>
	<body>
		<div class="father">
			<div class="son"></div>
		</div>
		<script>
			var father = document.querySelector(".father")
			var son = document.querySelector(".son")
			// 事件冒泡 :子标签发生事件以后，会将事件逐层传递给父标签。document  --- window
			//绝大部分的事件都会自动冒泡
			// onmouseenter 不会冒泡
			// onmouseover  会冒泡
			window.onmouseover = function(){
				console.log(111)
			}
		</script>
	</body>
</html>
